Additive manufacturing system having compaction nose

ABSTRACT

A head is disclosed for use with an additive manufacturing system. The head may include a nozzle through which material is discharged from the additive manufacturing system. The head may also include a nose located at a tip end of the nozzle, and a spring configured to bias the nose away from the nozzle.

RELATED APPLICATIONS

This application is based on and claims the benefit of priority from U.S. Provisional Application No. 62/417,709 that was filed on Nov. 4, 2016, the contents of which are expressly incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to a manufacturing system and, more particularly, to an additive manufacturing system having a compaction nose.

BACKGROUND

Extrusion manufacturing is a known process for producing continuous structures. During extrusion manufacturing, a liquid matrix (e.g., a thermoset resin or a heated thermoplastic) is pushed through a die having a desired cross-sectional shape and size. The material, upon exiting the die, cures and hardens into a final form. In some applications, UV light and/or ultrasonic vibrations are used to speed the cure of the liquid matrix as it exits the die. The structures produced by the extrusion manufacturing process can have any continuous length, with a straight or curved profile, a consistent cross-sectional shape, and excellent surface finish. Although extrusion manufacturing can be an efficient way to continuously manufacture structures, the resulting structures may lack the strength required for some applications.

Pultrusion manufacturing is a known process for producing high-strength structures. During pultrusion manufacturing, individual fiber strands, braids of strands, and/or woven fabrics are coated with or otherwise impregnated with a liquid matrix (e.g., a thermoset resin or a heated thermoplastic) and pulled through a stationary die where the liquid matrix cures and hardens into a final form. As with extrusion manufacturing, UV light and/or ultrasonic vibrations are used in some pultrusion applications to speed the cure of the liquid matrix as it exits the die. The structures produced by the pultrusion manufacturing process have many of the same attributes of extruded structures, as well as increased strength due to the integrated fibers. Although pultrusion manufacturing can be an efficient way to continuously manufacture high-strength structures, the resulting structures may lack the form (shape, size, and/or precision) required for some applications. In addition, during conventional multi-fiber pultrusion, ensuring adequate wetting and bonding between adjacent fibers can be problematic.

The disclosed system is directed to addressing one or more of the problems set forth above and/or other problems of the prior art.

SUMMARY

In one aspect, the present disclosure is directed to a head for an additive manufacturing system. The head may include a nozzle through which material is discharged from the additive manufacturing system. The head may also include a nose located at a tip end of the nozzle, and a spring configured to bias the nose away from the nozzle.

In another aspect, the present disclosure is directed to an additive manufacturing system. The additive manufacturing system may include a moveable support, and a nozzle operatively connected to the moveable support and configured to discharge material. The additive manufacturing system may also include a cure enhancer located adjacent the nozzle and configured to expose the material to cure energy during discharge, and a nose located at a tip end of the nozzle and being moveable relative to the nozzle to compact the material after discharge. The additive manufacturing system may further include a controller in communication with the moveable support and the cure enhancer. The controller may be configured to selectively activate the moveable support and the cure enhancer based on specifications for a structure to be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of an exemplary disclosed manufacturing system; and

FIGS. 2 and 3 are diagrammatic illustrations of exemplary disclosed heads that may be utilized with the manufacturing system of FIG. 1.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary system 10, which may be used to continuously manufacture a composite structure 12 having any desired cross-sectional shape (e.g., circular, polygonal, etc.). System 10 may include at least a support 14 and a head 16. Head 16 may be coupled to and moved by support 14. In the disclosed embodiment of FIG. 1, support 14 is a robotic arm capable of moving head 16 in multiple directions during fabrication of structure 12, such that a resulting longitudinal axis of structure 12 is three-dimensional. It is contemplated, however, that support 14 could alternatively be an overhead gantry or a hybrid gantry/arm also capable of moving head 16 in multiple directions during fabrication of structure 12. Although support 14 is shown as being capable of multi-axis movements, it is contemplated that any other type of support 14 capable of moving head 16 in the same or in a different manner could also be utilized, if desired. In some embodiments, a drive may mechanically couple head 16 to support 14, and may include components that cooperate to move and/or supply power or materials to head 16.

Head 16 may be configured to receive or otherwise contain a matrix material. The matrix material may include any type of matrix material (e.g., a liquid resin, such as a zero volatile organic compound resin; a powdered metal; etc.) that is curable. Exemplary matrixes include thermosets, single- or multi-part epoxy resins, polyester resins, cationic epoxies, acrylated epoxies, urethanes, esters, thermoplastics, photopolymers, polyepoxides, thiols, alkenes, thiol-enes, and more. In one embodiment, the matrix material inside head 16 may be pressurized, for example by an external device (e.g., an extruder or another type of pump—not shown) that is fluidly connected to head 16 via a corresponding conduit (not shown). In another embodiment, however, the pressure may be generated completely inside of head 16 by a similar type of device. In yet other embodiments, the matrix material may be gravity-fed through and/or mixed within head 16. In some instances, the matrix material inside head 16 may need to be kept cool and/or dark to inhibit premature curing; while in other instances, the matrix material may need to be kept warm for the same reason. In either situation, head 16 may be specially configured (e.g., insulated, chilled, and/or warmed) to provide for these needs.

The matrix material may be used to coat, encase, or otherwise surround any number of continuous reinforcements (e.g., separate fibers, tows, rovings, ribbons, and/or sheets of material) and, together with the reinforcements, make up at least a portion (e.g., a wall) of composite structure 12. The reinforcements may be stored within (e.g., on separate internal spools—not shown) or otherwise passed through head 16 (e.g., fed from external spools). When multiple reinforcements are simultaneously used, the reinforcements may be of the same type and have the same diameter and cross-sectional shape (e.g., circular, square, flat, etc.), or of a different type with different diameters and/or cross-sectional shapes. The reinforcements may include, for example, carbon fibers, vegetable fibers, wood fibers, mineral fibers, glass fibers, metallic wires, optical tubes, etc. It should be noted that the term “reinforcement” is meant to encompass both structural and non-structural types of continuous materials that can be at least partially encased in the matrix material discharging from head 16.

The reinforcements may be exposed to (e.g., coated with) the matrix material while the reinforcements are inside head 16, while the reinforcements are being passed to head 16 (e.g., as a pre-preg material), and/or while the reinforcements are discharging from head 16, as desired. The matrix material, dry reinforcements, and/or reinforcements that are already exposed to the matrix material (e.g., wetted reinforcements) may be transported into head 16 in any manner apparent to one skilled in the art.

The matrix material and reinforcement may be discharged from head 16 via at least two different modes of operation. In a first mode of operation, the matrix material and reinforcement are extruded (e.g., pushed under pressure and/or mechanical force) from head 16, as head 16 is moved by support 14 to create the 3-dimensional shape of structure 12. In a second mode of operation, at least the reinforcement is pulled from head 16, such that a tensile stress is created in the reinforcement during discharge. In this mode of operation, the matrix material may cling to the reinforcement and thereby also be pulled from head 16 along with the reinforcement, and/or the matrix material may be discharged from head 16 under pressure along with the pulled reinforcement. In the second mode of operation, where the matrix material is being pulled from head 16, the resulting tension in the reinforcement may increase a strength of structure 12, while also allowing for a greater length of unsupported material to have a straighter trajectory (i.e., the tension may act against the force of gravity to provide free-standing support for structure 12).

The reinforcement may be pulled from head 16 as a result of head 16 moving away from an anchor point 18. In particular, at the start of structure-formation, a length of matrix-impregnated reinforcement may be pulled and/or pushed from head 16, deposited onto anchor point 18, and cured, such that the discharged material adheres to anchor point 18. Thereafter, head 16 may be moved away from anchor point 18, and the relative movement may cause the reinforcement to be pulled from head 16. It should be noted that the movement of the reinforcement through head 16 could be assisted (e.g., via internal feed mechanisms), if desired. However, the discharge rate of the reinforcement from head 16 may primarily be the result of relative movement between head 16 and anchor point 18, such that tension is created within the reinforcement. It is contemplated that anchor point 18 could be moved away from head 16 instead of or in addition to head 16 being moved away from anchor point 18.

One or more cure enhancers (e.g., one or more light sources, an ultrasonic emitter, a laser, a heater, a catalyst dispenser, a microwave generator, etc.) 20 may be mounted proximate (e.g., within, on, and/or trailing from) head 16 and configured to enhance a cure rate and/or quality of the matrix material as it is discharged from head 16. Cure enhancer 20 may be controlled to selectively expose internal and/or external surfaces of structure 12 to energy (e.g., light energy, electromagnetic radiation, vibrations, heat, a chemical catalyst or hardener, etc.) during the formation of structure 12. The energy may increase a rate of chemical reaction occurring within the matrix material, sinter the material, harden the material, or otherwise cause the material to cure as it discharges from head 16.

A controller 22 may be provided and communicatively coupled with support 14, head 16, and any number and type of cure enhancers 20. Controller 22 may embody a single processor or multiple processors that include a means for controlling an operation of system 10. Controller 22 may include one or more general- or special-purpose processors or microprocessors. Controller 22 may further include or be associated with a memory for storing data such as, for example, design limits, performance characteristics, operational instructions, matrix characteristics, reinforcement characteristics, characteristics of structure 12, and corresponding parameters of each component of system 10. Various other known circuits may be associated with controller 22, including power supply circuitry, signal-conditioning circuitry, solenoid/motor driver circuitry, communication circuitry, and other appropriate circuitry. Moreover, controller 22 may be capable of communicating with other components of system 10 via wired and/or wireless transmission.

One or more maps may be stored in the memory of controller 22 and used during fabrication of structure 12. Each of these maps may include a collection of data in the form of models, lookup tables, graphs, and/or equations. In the disclosed embodiment, the maps are used by controller 22 to determine desired characteristics of cure enhancers 20, the associated matrix, and/or the associated reinforcements at different locations within structure 12. The characteristics may include, among others, a type, quantity, and/or configuration of reinforcement and/or matrix to be discharged at a particular location within structure 12, and/or an amount, intensity, shape, and/or location of desired compacting and curing. Controller 22 may then correlate operation of support 14 (e.g., the location and/or orientation of head 16) and/or the discharge of material from head 16 (a type of material, desired performance of the material, cross-linking requirements of the material, a discharge rate, etc.) with the operation of cure enhancers 20 such that structure 12 is produced in a desired manner.

Exemplary heads 16 are disclosed in detail in FIGS. 2 and 3. Head 16 may have a nozzle 26, through which matrix-wetted reinforcements are discharged. In one example, nozzle 26 is located at a lower end of a matrix reservoir 28, and at least partially surrounded by cure enhancers 20. The reinforcements may be received at an opposing upper end of reservoir 28, pass axially through reservoir 28 where at least some matrix-impregnation occurs, and be discharged from head 16 via nozzle 26.

Nozzle 26 of head 16 may include unique features that are configured to improve a quality of the material discharging from head 16. In particular, in some situations, it may be possible for the matrix-coated reinforcements to include voids (e.g., air bubbles), ridges, frayed ends, or other irregularities that inhibit adhesion between fibers or create uneven and rough surface textures. In these situations, pressing down on the discharged material prior to and/or during curing may improve the quality of structure 12. For this purpose, a nose 30 of nozzle 26 may be spring-biased axially downward (e.g., biased by one or more springs 32—downward with respect to the perspective of FIGS. 2 and 3) toward the discharging material. With this arrangement, nose 30 may ride over and exert a flattening or compacting force on the material just prior to the material curing fully. The flattening force may function to press out air bubbles, improve resin impregnation, consolidate loose fibers, and otherwise smooth surface features.

In the embodiment of FIG. 2, nose 30 is ring-like (e.g., annularly surrounding a tip end of nozzle 26) and flat at an axial end surface. In the embodiment of FIG. 3, nose 30 is frustoconical with a smaller axial end surface. In both embodiments, a material forming nose 30 may be relatively softer than a material forming a tip end of nozzle 26, such that nose 30 may wear away faster than nozzle 26. In this arrangement, nose 30 may function as a replaceable sacrificial layer that protects nozzle 26 from excessive wear. It should be noted that, in some embodiments, an internal annular edge of the tip end of nozzle 26 may be rounded to inhibit breakage of the reinforcements passing therethrough. In these embodiments, nose 30 may have a complimentary shape (e.g., a continuing radius), if desired.

Over a period of use, nose 30 may wear away and no longer have a shape and/or texture required for efficiently engaging the material discharging from nozzle 26. When this occurs, head 16 may be maneuvered (e.g., via support 14) over the top of a resurfacer 34 that is configured to restore an outer profile of nose 30 to a near-original shape, size, and/or texture. In the embodiment of FIG. 3, resurfacer 34 resembles a sharpener having one or more blades 36 that are positioned and/or oriented at precise locations for the particular configuration of nose 30. In other embodiments, however, resurfacer 34 could embody a sander, a hot iron, a mold, or another similar device.

It is contemplated that nose 30 may be coated with a substance that inhibits the matrix material from sticking to nozzle 26 during the pressing operation described above. For example, nose 30 may be coated with a release wax, petroleum jelly, a Teflon coating, etc. In this situation, resurfacer 34 may be further capable of reapplying that coating. For example, resurfacer 34 may include a spray jet, an orifice, or another mechanism that advances the coating onto nose 30 when nose 30 is brought near and/or into contact with resurfacer 34. Resurfacer 34 may be mounted on or adjacent support 14 (referring to FIG. 1), for example connected to a build chamber floor, wall, or other similar structure.

INDUSTRIAL APPLICABILITY

The disclosed systems may be used to continuously manufacture composite structures having any desired cross-sectional size, shape, length, density, and/or strength. The composite structures may include any number of different reinforcements of the same or different types, diameters, shapes, configurations, and consists, each coated with a common matrix material. In addition, the disclosed heads may allow for compaction and/or smoothing of structural surfaces and, thereby, an increased strength and/or performance. Operation of system 10 will now be described in detail.

At a start of a manufacturing event, information regarding a desired structure 12 may be loaded into system 10 (e.g., into controller 22 that is responsible for regulating operations of support 14 and/or head 16). This information may include, among other things, a size (e.g., diameter, wall thickness, length, etc.), a contour (e.g., a trajectory), surface features (e.g., ridge size, location, thickness, length; flange size, location, thickness, length; etc.), connection geometry (e.g., locations and sizes of couplings, tees, splices, etc.), desired weave patterns, weave transition locations, location-specific matrix stipulations, location-specific reinforcement stipulations, density stipulations, etc. It should be noted that this information may alternatively or additionally be loaded into system 10 at different times and/or continuously during the manufacturing event, if desired. Based on the component information, one or more different reinforcements and/or matrix materials may be selectively installed and/or continuously supplied into system 10.

Installation of the reinforcements may be performed by passing the reinforcements down through matrix reservoir 28, and then threading the reinforcements through nozzle 26. Installation of the matrix material may include filling head 16 and/or coupling of an extruder (not shown) to head 16.

Head 16 may then be moved by support 14 under the regulation of controller 22 to cause matrix-coated reinforcements to be placed against or on a corresponding anchor point 18. Cure enhancers 20 may then be selectively activated to cause hardening of the matrix material surrounding the reinforcements, thereby bonding the reinforcements to anchor point 18.

The component information may then be used to control operation of systems 10 and 12. For example, the reinforcements may be pulled and/or pushed from head 16 (along with the matrix material), while support 14 selectively moves head 16 in a desired manner during curing, such that an axis of the resulting structure 12 follows a desired trajectory (e.g., a free-space, unsupported, 3-D trajectory). As the separate reinforcements are pulled through head 16, the reinforcements may pass under nose 30 and be flattened and/or compressed into a desired thickness and/or contour. Once structure 12 has grown to a desired length, structure 12 may be disconnected (e.g., severed) from head 16 in any desired manner.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed systems and head. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed systems and heads. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents. 

What is claimed is:
 1. A head for an additive manufacturing system, comprising: a nozzle through which material is discharged from the additive manufacturing system; a nose located at a tip end of the nozzle; and a spring configured to bias the nose away from the nozzle.
 2. The head of claim 1, wherein the nose annularly surrounds the tip end of the nozzle.
 3. The head of claim 2, wherein the nose is ring-like and flat at an axial end surface.
 4. The head of claim 2, wherein the nose is frustoconical.
 5. The head of claim 1, wherein an end surface of the nose is coated with a substance that inhibits the material from sticking to the nose.
 6. The head of claim 5, wherein the substance includes at least one of release wax, petroleum jelly, and a Teflon coating.
 7. The head of claim 1, wherein a material forming the nose is softer than a material forming the tip end of the nozzle.
 8. The head of claim 1, further including a matrix reservoir located at a side of the nozzle opposite the nose.
 9. The head of claim 1, further including at least one cure enhancer connected to the nozzle and oriented to expose the material to cure energy during discharge.
 10. An additive manufacturing system, comprising: a moveable support; a nozzle operatively connected to the moveable support and configured to discharge material; a cure enhancer located adjacent the nozzle and configured to expose the material to cure energy during discharge; a nose located at a tip end of the nozzle and being moveable relative to the nozzle to compact the material after discharge; and a controller in communication with the moveable support and the cure enhancer, the controller being configured to selectively activate the moveable support and the cure enhancer based on specifications for a structure to be manufactured.
 11. The additive manufacturing system of claim 10, wherein the cure enhancer is located to expose the material to cure energy after the material has been compacted by the nose.
 12. The additive manufacturing system of claim 10, further including a spring configured to bias the nose away from the nozzle.
 13. The additive manufacturing system of claim 10, wherein the nose annularly surrounds a tip end of the nozzle.
 14. The additive manufacturing system of claim 13, wherein the nose is ring-like and flat at an axial end surface.
 15. The additive manufacturing system of claim 13, wherein the nose is frustoconical.
 16. The additive manufacturing system of claim 10, wherein an end surface of the nose is coated with a substance that inhibits the material from sticking to the nose.
 17. The additive manufacturing system of claim 16, wherein the substance includes at least one of release wax, petroleum jelly, and a Teflon coating.
 18. The additive manufacturing system of claim 10, wherein a material forming the nose is softer than a material forming the nozzle.
 19. The additive manufacturing system of claim 10, further including a matrix reservoir located at a side of the nozzle opposite the nose.
 20. The additive manufacturing system of claim 10, further including a resurfacer configured to restore an outer profile of the nose. 